Foamable compositions comprising ethylene and foaming/blowing agents have been used in wire and cable applications to make insulation and jacketing. However, foamability of polyethylene (PE) has been problematic.
Attempts have been made to improve the foamability of polyethylene by optimizing PE chain architecture (e.g., chain length, branching, etc.) in connection with the choice of foaming/blowing agents. To date, the most effective means to improve the foamability of polyethylene has been through the use of high melt strength low density polyethylene (LDPE).
High density polyethylene (HDPE) is a cost effective material and has the advantage of providing desired stiffness and rigidity to support the conductor of a wire or cable. However, HDPE is more difficult to foam compared to LDPE or LLDPE, especially when used in conjunction with a chemical foaming/blowing agent due to its semi-crystalline nature.
From an industry standpoint, it would be desirable to provide a material based on HDPE with improved foamability and high processability that can be used in fabricating extruded or molded cable components having reduced (low) weight and a balance of overall performance attributes.